The picture above illustrates the hydrogenation of a carbon-carbon double bond (specifically, Hydrogenation of the Alkene, Ethene). This process can also be seen when converting vegetable oils to margarine. The addition of hydrogen makes straight chain hydrocarbons where the structure of the once vegetable oil becomes more solid.
In general, how do these catalyst work?
Heterogeneous Catalysis:
- One or more of the reactants become adsorbed* on to the catalytic surface, the places where they are absorbed are called active sites
- There are interactions occurring on the surface which make the reactant molecules bonds weaker or which make them break
- The reaction takes place: new bonds are formed on the surface
- The product then deadsorbs of the surface and more active sites are made available for more reactants
How does it Increase the rate of reaction?
1) the adsorption onto the surface concentrates the reactant (brings them closer), increasing likelihood of collisions
2) weakens the bonds: making reactions easier
3) repositions molecules, which results in more preferred orientations
Heterogeneous Catalysis:
- One or more of the reactants become adsorbed* on to the catalytic surface, the places where they are absorbed are called active sites
- There are interactions occurring on the surface which make the reactant molecules bonds weaker or which make them break
- The reaction takes place: new bonds are formed on the surface
- The product then deadsorbs of the surface and more active sites are made available for more reactants
How does it Increase the rate of reaction?
1) the adsorption onto the surface concentrates the reactant (brings them closer), increasing likelihood of collisions
2) weakens the bonds: making reactions easier
3) repositions molecules, which results in more preferred orientations
*Adsorbed: many confuse this word with absorbed, although to be adsorbed is when a molecule or object is sticking to a surface compared to being dissolved into a surface